Assessment of closed cycles operating with supercritical CO2 as bottoming of small combustion turbines

Abstract

This work investigates the performance of supercritical CO2 power cycles bottoming small combustion turbines. As a matter of fact, the maximum power output of the topping cycle is limited to 10 MW, since there is a great number of commercial combustion turbine units for which the conventional combined cycle architecture with a bottoming steam power plant is not convenient. In detail, the partial heating cycle is the layout chosen for this study according to the interesting trade-off between heat recovery and cycle efficiency, with a limited number of components. Considering the investigated range of power production, single-stage radial turbomachines are selected and their efficiency values are not fixed at first glance but result from actual size and running conditions, based on flow rates, enthalpy variations as well as rotational speeds. Focusing on a number of cases, interesting considerations about the size of the components of the supercritical CO2 power cycle are possible thanks to the theory of similitude.